{"id":"CVE-2026-54412","details":"LiamBindle MQTT-C through version 1.1.6 contains a heap-based out-of-bounds read and integer underflow in the mqtt_unpack_publish_response() function in src/mqtt.c that allows a remote unauthenticated attacker controlling an MQTT broker - or able to inject MQTT traffic into an unencrypted session - to crash a subscribed MQTT-C client and potentially disclose adjacent heap memory by sending a single crafted PUBLISH packet. The function validates only that the fixed-header remaining_length is at least 4, then reads the 16-bit topic_name_size field from the broker-controlled packet and advances the parse pointer by that value without verifying that topic_name_size plus the surrounding overhead fits within remaining_length; it subsequently computes application_message_size as remaining_length - topic_name_size - 2 (QoS 0) or - 4 (QoS greater than 0) in unsigned arithmetic, producing an integer underflow that is then passed to memmove(). A PUBLISH packet with topic_name_size = 0xFFFF and remaining_length = 7 advances the parse pointer 65535 bytes past the receive buffer (out-of-bounds read) and causes an application_message_size near 2^32, crashing the process when the resulting memmove() is executed.","modified":"2026-07-08T08:14:06.405194415Z","published":"2026-06-14T17:26:36.740Z","database_specific":{"cna_assigner":"TuranSec","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54412.json","cwe_ids":["CWE-125","CWE-191"]},"references":[{"type":"WEB","url":"https://github.com/LiamBindle/MQTT-C/blob/v1.1.6/src/mqtt.c#L1334"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54412.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54412"},{"type":"PACKAGE","url":"https://github.com/LiamBindle/MQTT-C"},{"type":"ARTICLE","url":"https://cwe.mitre.org/data/definitions/125.html"},{"type":"ARTICLE","url":"https://cwe.mitre.org/data/definitions/191.html"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/liambindle/mqtt-c","events":[{"introduced":"0"},{"fixed":"f69ce1e7fd54f3b1834c9c9137ce0ec5d703cb4d"}],"database_specific":{"source":["AFFECTED_FIELD","DESCRIPTION"],"extracted_events":[{"introduced":"0"},{"last_affected":"1.1.6"},{"fixed":"1.1.6"}]}}],"versions":["1.1.5","1.1.4","1.1.3","1.1.2","1.1.1","1.1.0","1.0.3","1.0.2","1.0.1","1.0.0","v1.1.0","v1.0.3","v1.0.2","v1.0.1","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54412.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/AU:Y/V:D"}]}